chapter 22

A farmer uses triazine herbicide to control pigweed in his field. For the first few years, the triazine works well and almost all the pigweed dies; but after several years, the farmer sees more and more pigweed. Which of these explanations best explains what happened?

triazine-resistant weeds were more likely to survive and reproduce.

If x indicates the fossils of two closely related species, neither of which is extinct, then their remains may be found in how many of these strata? a b x c d

two strata

with what other idea of his time was cuvier's theory of catastrophism most in conflict?

unifromitarianism

Which of the following scientists argued that variation among individuals allows evolution to occur?

wallace

in the mid 1990s the soviet geneticist Lysenko believed that his winter wheat plants, exposed to increasingly colder temperatures, would eventually give rise to more cold-tolerant winter wheat. lysenkos attempts in this regard were most in agreement with the ideas of

lamarck

Given a population that contains genetic variation, what is the correct sequence of the following events under the influence of natural selection? 1. Well-adapted individuals leave more offspring than do poorly adapted individuals. 2. A change occurs in the environment. 3. Genetic frequencies within the population change. 4. Poorly adapted individuals have decreased survivorship.

2 → 4 → 1 → 3

Which of these conditions are always true of populations evolving due to natural selection? Condition 1: The population must vary in traits that are heritable. Condition 2: Some heritable traits must increase reproductive success. Condition 3: Individuals pass on most traits that they acquire during their lifetime.

Conditions 1 and 2

If Darwin had been aware of genes and their typical mode of transmission to subsequent generations, with which statement would he most likely have been in agreement?

If natural selection can change gene frequency in a population over generations, given enough time and genetic diversity, then natural selection can cause sufficient genetic change to produce new species from old ones.

Starting from the wild mustard Brassica oleracea, breeders have created the strains known as Brussels sprouts, broccoli, kale, and cabbage. Therefore, which of the following statements is correct?

In this wild mustard, there is enough heritable variation to permit these different varieties.

Which of the following represents an idea that Darwin learned from the writings of Thomas Malthus?

Populations tend to increase at a faster rate than their food supply normally allows.

Parasitic species tend to have simple morphologies. Which of the following statements best explains this observation?

Simple morphologies convey some advantage in most parasites.

Currently, two extant elephant species (X and Y) are classified in the genus Loxodonta, and a third species (Z) is placed in the genus Elephas. Thus, which statement should be true?

Species X and Y share a greater number of homologies with each other than either does with species Z.

A biologist studied a population of squirrels for fifteen years. During that time, the population was never fewer than thirty squirrels and never more than forty-five. Her data showed that over half of the squirrels born did not survive to reproduce, because of both competition for food and predation. In a single generation, 90% of the squirrels that were born lived to reproduce, and the population increased to eighty. Which inference(s) about this most recent surge in the population size might be true?

The amount of available food may have increased and/or the predators that prey upon squirrels may have decreased.

Claytonia virginica is a woodland spring herb with flowers that vary from white to pale pink to bright pink. Slugs prefer to eat pink-flowering over white-flowering plants (due to chemical differences between the two), and plants experiencing severe herbivory are more likely to die. The bees that pollinate this plant also prefer pink to white flowers, so that Claytonia with pink flowers have greater relative fruit set than Claytonia with white flowers. A researcher observes that the percentage of different flower colors remains stable in the study population from year to year. Given no other information, if the researcher removes all slugs from the study population, what do you expect to happen to the distribution of flower colors in the population over time?

The percentage of pink flowers should increase over time.

prior to the work of lyell and darwin the prevailing belief was that Earth is ___

a few thousand years old, and populations are unchanging

Many crustaceans (for example, lobsters, shrimp, and crayfish) use their tails to swim, but crabs have reduced tails that curl under their shells and are not used in swimming. This is an example of _____.

a vestigial trait

A population of organisms will not evolve if _____

all individual variation is due only to environmental factors

The cow Bos primigenius (which is bred for meat and milk) has a smaller brain and larger eyes than closely related wild species of ungulates. These traits most likely arose by _____.

artificial selection, because changes in these traits co-occurred with human selection for high milk output and high muscle content

If x indicates the location of fossils of two closely related species, then fossils of their most recent common ancestor are most likely to occur in which stratum? a b x c d

c

"the giraffe stretched its neck while reaching for higher leaves; its offspring inherited longer necks as a result" which statement is most likely to be helpful in correcting this misconception

characteristics acquired during an organisms life are generally not passed on through genes

The role that humans play in artificial selection is to _____.

choose which organisms reproduce

Cotton-topped tamarins are small primates with tufts of long white hair on their heads. While studying these creatures, you notice that males with longer hair get more opportunities to mate and father more offspring. To test the hypothesis that having longer hair is adaptive in these males, you should _____.

determine if hair length is heritable

darwin and wallace's theory of evolution by natural selection was revolutionary because it _____

dismissed the idea that species are constant and emphasized the importance of variation and changed through time

Which of the following, if discovered, could refute our current understanding of the pattern of evolution?

diverse fossils of mammals in Precambrian rock

After the drought of 1977, researchers on the island of Daphne Major hypothesized that medium ground finches that had large, deep beaks, survived better than those with smaller beaks because they could more easily crack and eat the tough Tribulus cistoides fruits. If this hypothesis is correct, what would you expect to observe if a population of these medium ground finches colonizes a nearby island where Tribulus cistoides is the most abundant food for the next 1000 years? Assume that (1) even the survivors of the 1977 drought sometimes had difficulty cracking the tough T. cistoides fruits and would eat other seeds when offered a choice; and (2) food availability is the primary limit on finch fitness on this new island.

evolution of yet larger, deeper beaks over time

Which of the following must exist in a population before natural selection can act upon that population?

genetic variation among individuals

After the drought of 1977, researchers hypothesized that on the Galápagos island Daphne Major, medium ground finches with large, deep beaks survived better than those with smaller beaks because they could more easily crack and eat the tough Tribulus cistoides fruits. A tourist company sets up reliable feeding stations with a variety of bird seeds (different types and sizes) so that tourists can get a better look at the finches. Which of these events is now most likely to occur to finch beaks on this island?

increased variation in beak size and shape over time

Fossils of Thrinaxodon, a species that lived during the Triassic period, have been found in both South Africa and Antarctica. Thrinaxodon had a reptile-like skeleton and laid eggs, but small depressions on the front of its skull suggest it had whiskers and, therefore, fur. Thrinaxodon may have been warm-blooded. The fossils of Thrinaxodon are consistent with the hypothesis that _____.

mammals evolved from a reptilian ancestor

Darwin and Wallace were the first to propose _____.

natural selection as the mechanism of evolution

when cuvier considered the fossils found in the vicinity of paris he concluded that the extinction of species ___

occurs, but that there is no evolution

In a hypothetical environment, fishes called pike-cichlids are visual predators of large, adult algae-eating fish (in other words, they locate their prey by sight). The population of algae-eaters experiences predatory pressure from pike-cichlids. Which of the following is least likely to result in the algae-eater population in future generations?

selection for larger female algae-eaters, bearing broods composed of more, and larger, young

Which of Darwin's ideas had the strongest connection to his reading of Malthus's essay on human population growth?

struggle for existence

catastrophism was cuvier's theory of catastrophism most in conflict?

the fossil record